Removable shield means for vacuum switch bellows



April 22, 1969 H. J. WESOLOSKI REMOVABLE SHIELD MEANS FOR VACUUM SWITCHBELLOWS Filed Aug. 8, 1966 United States Patent US. Cl. 200-144 2 ClaimsABSTRACT OF THE DISCLOSURE A vacuum interrupter comprises a cylindricalglass envelope with an opening at one end. A first cylindrical metalring is bonded to the envelope around the opening. A second cylindricalring, internally threaded, is secured to the first ring and extends backinto the envelope. A movable contact rod extends into the envelopethrough the opening. A cylindrical bellows surrounds the rod and extendsbeyond the glass envelope and the first ring. One end of the bellows isjoined to the second ring inside the envelope and to the rod outside ofthe envelope. An externally threaded cylindrical shield attaches to thethreads on the second ring and surrounds and protects the bellows.Flanged attachment means for the vacuum interrupter are provided on theshield.

ing member such as a bellows is arranged between the envelope and themovable contact rod to provide a vacuum tight connection therebetweenwhile still permitting movement of the movable contact. Since thebellows is very fragile, it was practical to situate the bellowssubstantially Within the end of the envelope to protect it againstdamage. However, this made the bellows relatively hard to get at forwelding during manufacture of the switch, particularly when chill ringsused for cooling during welding to protect other components wereemployed.

Accordingly, it is an object of the present invention to provide avacuum switch in which the bellows are located in a more accessibleposition for welding during assembly or repair.

Another object is to provide improved means for sealing the openingbetween a vacuum switch envelope and the movable contact rod.

Another object is to provide improved means for shielding vacuum switchbellows against physical damage.

Another object is to provide improved bellows shielding means of theaforesaid character which also adapt the vacuum switch for mounting on asuitable supporting stud.

Another object is to provide a shield of the aforesaid character whichis removable.

Other objects and advantages of the invention will hereinafter appear.

The accompanying drawing illustrates a preferred embodiment of theinvention but it is to be understood that the embodiment illustrated issusceptible of modifications with respect to details thereof withoutdeparting from the scope of the appended claims.

In the drawing there is shown a cross sectional view of a vacuum switchembodying the present invention.

Referring to the drawing, the numeral designates a vacuum switchenvelope which, for example, is made of glass but could be made of othermaterials. An electrically conductive stationary contact rod or contactsupport member 12 having a contact 14 thereon extends into one end ofenvelope 10 and is sealed thereto as at 16. An electrically conductiveaxially movable contact rod or contact support member 18 having -acontact 20 thereon extends into the other end of envelope 10. Movablecontact rod 18 has a portion 19 to which an electrical conductor andoperating linkage can be connected.

Means are provided to form a vacuum tight seal between envelope 10 andmovable contact rod 18. Such means comprise first metal ring 22 whichhas one end connected by a metal-to-glass seal, as at 24, to envelope10. A second metal ring 26 is secured in vacuum tight connection to ring22 as by welding. Ring 26 is provided with an aperture 27 foraccommodating movable contact rod 18. If preferred, the rings 22 and 26could be integrally formed of a single piece of metal. An arcing shield28 is provided within envelope 10 and supported on ring 26 to preventarcing products produced during contact separation from being depositedon the inside surface of envelope 10. A hearing washer 30 is supportedwithin arcing shield 28 to guide and support movable contact 18'. Aflexible sealing member, such as a generally cylindrical corrugatedbellows 32 has one end secured in vacuum tight connection, as by weldingat 34, to ring 26. The other end of bellows 32 is secured in vacuumtight connection, as by welding at 36 and 38, to movable contact rod 18and to a washer 40, respectively. Washer 40 is secured to rod 18 as bywelding at 42.

In accordance with the present invention removable shield means 44,tubular in form, are provided to protect bellows 32, particularly thatportion of the bellows which, in the absence of shield 44, would projectbeyond envelope 10 and the rings 22 and 26. Means are provided toremovably attach shield 44 to envelope 10 and such means take the formof a threaded portion 46 on shield 44 and a corresponding threadedportion 48 on ring 26. Shield 44 is further provided with means, such asa flange 50 having mounting holes 52 therein, which adapt the vacuumswitch for mounting on a suitable support (not shown).

As will be understood, shield 44 is not attached during manufactureuntil the various welds described herein have been made. Consequently,the welding gun has access to the areas where welds are desired.Furthermore, the absence of shield 44 permits. chill rings to betemporarily placed in appropriate positions during welding to preventthe metal-to-glass seal 24 from being damaged by heat stress. Shield 44is put in place as shown in the drawing only after all welds are madeand the tube is evacuated and baked out. If preferred, a joint sealingcompound such as Locktite can be used on the threaded portions of shield44 and ring 26 to prevent the shield from working loose.

As will be further understood, shield 44 can be removed aftermanufacture to make repairs to bellows 32 or to any weld which sorequires.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:

1. In a vacuum interrupter, an envelope having an opening, a tubularmeans sealed to said envelope at said opening and having a portionextending inside said envelope,

connecting means on the inside of said tubular means at said portionthereof which extends inside said envelope,

a movable contact support member extending into said envelope throughsaid opening and having a portion extending outside of said envelope,

a tubular corrugated bellows surrounding said member and having aportion outside of said envelope,

said bellows connected to the portion of said tubular means inside saidenvelope and connected to the portion of said contact support memberoutside of said envelope, a detachable tubular shield surrounding atleast the portion of said bellows outside of said envelope, said shieldhaving connecting means on the exterior thereof for engaging with theconnecting means on said tubular means,

and means on said shield for connecting said vacuum interrupter to asupport.

2. In a vacuum interrupter,

an envelope of insulating material and having an opena first ring havingone end sealed to said envelope and extending outwardly therefrom,

a second ring which extends inside said envelope and has one end sealedto the other end of said first ring,

threaded connecting means on the inside of said second ring at theportion thereof which extends inside said envelope,

a movable contact support member extending into said envelope throughsaid opening and having a portion extending outside of said envelopebeyond the other end of said first ring,

a tubular corrugated bellows surrounding said contact support member andhaving a portion outside of said envelope beyond the other end of saidlfilSt ring,

said bellows connected at one end to the other end of said second ringinside said envelope and connected at its other end to a portion of saidcontact support member outside of said envelope beyond the other end ofsaid first ring,

a detachable tubular shield surrounding said bellows and extendingbeyond the other end of said first threaded connecting means on theexterior of said shield for engaging with the threaded connecting meanson said second ring,

and flange means on said shield for connecting said vacuum interrupterto a support.

References Cited UNITED STATES PATENTS 2,966,569 12/1960 Jennings.2,979,587 4/1961 Jennings.

25 ROBERT S. MACON, Primary Examiner.

